"Dominika's a good opponent and it was a really good match," Bertens said. "She was playing well so I got nervous the last game, but I'm happy I managed to keep serving well and I'm happy with the win."

Magdalena Rybarikova completed a day to forget for Slovakia as she retired hurt at 4-0 down in the first set against Errani.

Errani suffered a first round loss to Carla Suárez Navarro at the Australian Open but the top seed will get a chance for some revenge in the quarter-finals.

Errani said: "The next match is going to be interesting because I know Carla very well and she beat me at the Australian Open. I like this surface and I just want to keep playing my game, and we will see how it goes tomorrow."

There was also woe for eighth-seeded Czech Klara Zakopalova as she went down to Spaniard Carla Suarez Navarro.